A NEW BREAKPOINT, TELOMERIC TO TEL ETV6, ON THE SHORT ARM OF CHROMOSOME-12 IN T-CELL ACUTE LYMPHOBLASTIC-LEUKEMIA/

Abnormalities of the short arm of chromosome 12 frequently involve the TEL/ETV6 gene in acute leukemias. In two cases of T cell acute lympho blastic leukemia with translocation t(12;14)(p13;q11) and t(7;12)(q35; p13), respectively, the breakpoints were located telomeric to the TEL/ ETV6 locus. Further fluorescence in situ hybridization (FISH) studies showed that the breakpoint was located between two markers, FGF6 (cent romeric) and D12S983 (telomeric) on 12p in both patients. This result suggests that a new chromosomal breakpoint can nonrandomly involve rea rrangements in T cell malignancies. The breakpoint on chromosome 14 wa s localized centromeric to the TRCA/D locus.